Hi
Storyboard is buggy yes, trying to reorganize frames from story board can generate lose of frames, I already experimented it 
Concerning the lost related to “moving the timeline”, I can’t tell there a bug or not, but I think a precise explanation about what has been done to be able to reproduce and understand the problem could help.
Also, what “moving the time line” exactly means? 
What has been lost?
Only content from a layer? Content for all layer?
All layer deleted?
All frames deleted?
Grum999